Winter supplementation affects calving

A set of Brangus heifers in the brush covered in sleet. Photo by Dr. Joe Paschal

It doesn’t get as cold for as long in the South as it does farther north, but the change in season and cooler if not wintry weather affects grass growth and quality all the same.

Depending on when you calve, you might have pairs on the ground already or possibly some mid- to late-bred cows (or for some of you, a mix). At any rate, with the onset of cooler weather or possibly even a frost, grass growth has ceased, and the quality (protein and energy) of the standing forage from summer grasses has dropped significantly.

If you calve in the spring, your cows are likely in mid-to-late gestation and, if you have adequate grass, will require some protein supplementation to ensure they maintain their body condition and have enough nutrients for their developing calves.

If you calve in the fall and have young calves already on the ground, the protein requirements of their dams will be substantially higher, about double the supplementation required by dry-bred cows. If cows are deficient in protein, protein supplementation can improve the digestibility of lower-quality forages by 30 percent or more.

The whole purpose of a winter supplementation program is to maintain or improve cow body condition (fatness). Fatness is an indicator of energy stores, so thin cows aren’t necessarily protein-deficient; they are energy-deficient. Cows with higher body condition scores are more likely to rebreed sooner after calving, while cows that calve in higher BCS generally have less calving difficulty and stronger calves and produce more and higher-quality colostrum (first milk), essential for healthy calves.

Gestating cows with higher BCS supply more nutrients to their unborn calves, providing them an opportunity to grow and be healthy from the very start.

Supplementing high-quality (and nutrient-tested) hay might be enough for cows in good condition (no ribs showing), but cows in thin condition could benefit from both protein and energy supplementation.

There are many ways to supplement protein (and energy) to your cowherd. All of them are acceptable to meet their needs, but some may cost a little more than others. The cost of labor and transportation must be figured into the equation. More expensive supplements that are self-fed can be cost-effective if you must travel to supplement every day.

Many years ago, researchers at Texas A&M found that protein supplementation can be doubled or tripled up and fed every other day or every third day without any negative effect on the nutrient levels in the cow. If you are hand-feeding supplement out of a sack, I would also recommend that some sort of feed troughs be considered. It doesn’t take long to pay for several troughs.

Winter pasture can be an excellent source early on for protein and then later for energy, but we waste a lot of this expensive feed. Research has shown cows fulfill their protein requirements with about an hour’s worth of grazing. Grazing cows for a couple of hours every other day will meet their protein requirements easily and prolong the use of the pasture by reducing plant loss due to trampling, crushing and fecal or urine patches.

If you are supplementing long-bred cows, research shows calving can be affected by time of supplementation.

Supplementing cattle in the late afternoon tends to push cows and heifers that would have calved that night into the daylight hours of the next day.

Feeding in the afternoon also makes the cows eat more forage during the day.

Both factors are worth considering.

Merry Christmas to you all.

Joe Paschal is a livestock specialist at Texas A&M AgriLife Extension in Corpus Christi. He can be contacted at 361-265-9203 or email j-paschal@tamu.edu.

For more information regarding news from the Department of Animal Science, College of Agriculture and Life Sciences, Texas A&M University, please contact Maggie Tucker at maggie.tucker@tamu.edu or (979) 845-1542.